Determination of uric acid by chemiluminescence measurement using tris(2,2′-bipyridine)ruthenium(II)-octylphenylpolyglycoI ether system

The determination of uric acid in urine samples was studied by a chemiluminescence measurement using tris (2,2'-bipyridine)ruthenium(II)-octylphenylpolyglycolether [Ru(bpy)(3)(2+)-OPE] system. The oxidized uric acid by Ce(IV) excited Ru(bpy)(3)(2+) to emit a chemiluminescence in this system so that the intensity was stoichiometrically dependent upon the concentration of uric acid. In a reaction cell, a luminescent reagent, oxidant, surfactant and sulfuric acid were flowed into and mixed with a taken sample. Experimental conditions were optimized to obtain the maximum intensity of chemiluminescence. Each reactant solution of more than the following concentration gave a good result: 2 x 10(-4) M Ru(bpy)(3)(2+), 0.01 M Ce(IV), 6% OPE, and 0.33 M H2SO4. Any interferences were not shown in this process by the investigation of concomitant constitutes such as albumin, creatine, lactic acid, glucose, urea, Cl-, Mg2+, Ca2+ and so on. The linearity of a calibration curve was good with r = 0.998, the relative standard deviation of the slope was 3.3% and the detection limit was 5.6 ng/mL. The recoveries of 80 to 91% were obtained from the standard spiked samples. The values were little bit low, but this procedure could be considered to be reliable for the determination of trace uric acid in urine samples.